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Effect of diet differences and non-native prey consumption on the productivity of small herons
Title
Effect of diet differences and non-native prey consumption on the productivity of small herons.
Creator
Jackson, Ashley Elizabeth, Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Environmental Studies
Abstract/Description
Little Blue Herons, Snowy Egrets, and Tricolored Herons that nest in the Everglades have declined sharply over the past decade, due in part to food resource limitations. Here, I examined the diet of small herons to determine how prey characteristics affected the fitness of small herons in the highly modified Florida Everglades. Analysis of these diet differences showed birds nesting in 2017, a hydrologically dryer-than average year, and a more taxonomically varied diet were associated with...
Show moreLittle Blue Herons, Snowy Egrets, and Tricolored Herons that nest in the Everglades have declined sharply over the past decade, due in part to food resource limitations. Here, I examined the diet of small herons to determine how prey characteristics affected the fitness of small herons in the highly modified Florida Everglades. Analysis of these diet differences showed birds nesting in 2017, a hydrologically dryer-than average year, and a more taxonomically varied diet were associated with nest success and improved body condition of nestlings. Over half (51%) of the fish biomass Little Blue Herons consumed were non-native species, compared to 14% and 19% non-native fish biomass consumed by Snowy Egrets and Tricolored Herons, respectively. Surprisingly, <7% of fish biomass available in the Everglades were comprised of non-native fish species, suggesting that small herons, and Little Blue Herons in particular, may be using alternative foraging habitats, to supplement their dietary needs.
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013072
Subject Headings
Herons, Florida--Everglades., Herons--Ecology.
Format
Document (PDF)
FORAGING ECOLOGY OF A WADING BIRD IN TIDALLY INFLUENCED HABITATS: A SEQUENTIAL MODELING FRAMEWORK
Title
FORAGING ECOLOGY OF A WADING BIRD IN TIDALLY INFLUENCED HABITATS: A SEQUENTIAL MODELING FRAMEWORK.
Creator
Martinez, Marisa Takada, Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
I used empirical data to inform spatially- and temporally-explicit predictions of time-integrated habitat availability (TiHAB), quantify spatiotemporal patterns of resource selection by Little Blue Herons (Egretta caerulea), and evaluate foraging activity as function of resource availability and prey dynamics. Evaluating resource availability over time accounts for the magnitude and duration of resource change. This approach is useful for understanding mechanisms that underlie resource...
Show moreI used empirical data to inform spatially- and temporally-explicit predictions of time-integrated habitat availability (TiHAB), quantify spatiotemporal patterns of resource selection by Little Blue Herons (Egretta caerulea), and evaluate foraging activity as function of resource availability and prey dynamics. Evaluating resource availability over time accounts for the magnitude and duration of resource change. This approach is useful for understanding mechanisms that underlie resource selection in dynamic environments and for guilds that are sensitive to changes in prey availability like wading birds. I found that average TiHAB varied interannually whereby gains and losses in Little Blue Heron foraging habitat at the landscape scale (1-8 km) occurred from slight differences in annual tidal cycles otherwise imperceptible with water depth data alone. Local patterns of resource selection by Little Blue Herons were temporally consistent but spatially variable across tidally influenced environments. TiHAB was the most important habitat attribute over time and space and was superior to other environmental features and prey density as a predictor of Little Blue Heron resource selection. Foraging activity did not show a clear association with probability of resource selection, but foraging metrics were best described by changes in TiHAB consistent with changes in foraging strategy. I conclude that spatiotemporal variation in resource availability reliably predicts patterns of dynamic habitat selection and supports an energy-maximizing foraging strategy for wading birds in tidally influenced habitats. This modeling framework can be applied to quantify the spatiotemporal availability of resources in real-time or under hydrologic restoration regimes and sea level rise scenarios, and track species responses to hydrologic and other environmental fluctuations.
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Date Issued
2022
PURL
http://purl.flvc.org/fau/fd/FA00013925
Subject Headings
Ecology, Herons, Wading birds, Ecological modelling
Format
Document (PDF)
Leiocephalus Carinatus Armouri (Northern curly-tailed lizard). Terrestrial predation by a juvenile wading bird
Title
Leiocephalus Carinatus Armouri (Northern curly-tailed lizard). Terrestrial predation by a juvenile wading bird.
Creator
Smith, Henry T., Engeman, Richard M.
Date Issued
2004-05
PURL
http://purl.flvc.org/fcla/dt/11528
Subject Headings
Curlytail lizards, Lizards--Florida, Leiocephalus, Herons, Predation
Format
Document (PDF)
Diet and Nesting Habitat of Wading Birds in a Shallow, Eutrophic Lake
Title
Diet and Nesting Habitat of Wading Birds in a Shallow, Eutrophic Lake.
Creator
May, Jenna C., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Avian reproductive success varies depending on environmental conditions, degree of predation, location, and food availability. I examined food availability and nesting habitat of wading birds in South Florida. Evaluating prey availability and prey used by two small heron species demonstrated the ability for small herons to maintain consistent diets through fluctuating environmental conditions, within and across different wetland types. Small herons may be able to cope with environmental...
Show moreAvian reproductive success varies depending on environmental conditions, degree of predation, location, and food availability. I examined food availability and nesting habitat of wading birds in South Florida. Evaluating prey availability and prey used by two small heron species demonstrated the ability for small herons to maintain consistent diets through fluctuating environmental conditions, within and across different wetland types. Small herons may be able to cope with environmental changes by altering foraging locations and strategies. Regarding nesting habitat, man-made sites may provide habitat comparable to natural sites, at least in the short-term. The nest’s position can influence its susceptibility to increased temperatures and predators, particularly for. Climatic conditions such as rainfall can also impact nesting success by altering foraging conditions and fish behavior. Understanding the effects of hydrologic regimes on biota can have practical applications since ecosystems around the world share similar problems with competing demands for resources, and there is a concern for how use can affect the quality of the resource.
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013087
Subject Headings
Wading birds., Herons--Ecology., Okeechobee, Lake (Fla.)
Format
Document (PDF)
Wading bird use of geographically isolated wetlands in the southeastern U.S. Coastal Plain
Title
Wading bird use of geographically isolated wetlands in the southeastern U.S. Coastal Plain.
Creator
Herteux, Camille E., Gawlik, Dale E., Smith, Lora L., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Geographically isolated wetlands (GIWs) within the southeastern U.S. Coastal Plain have been increasingly recognized for their importance in providing ecosystem services. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. I quantified wading bird presence in GIWs in southwestern Georgia and determined the relative importance of factors influencing their use of these wetlands. I also examined the diet of a nesting colony of...
Show moreGeographically isolated wetlands (GIWs) within the southeastern U.S. Coastal Plain have been increasingly recognized for their importance in providing ecosystem services. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. I quantified wading bird presence in GIWs in southwestern Georgia and determined the relative importance of factors influencing their use of these wetlands. I also examined the diet of a nesting colony of Little Blue Herons; a species experiencing population declines throughout most of the Southeast. I found that wetland-specific parameters were important factors in predicting wading bird use of GIWs, and wading birds utilized agricultural and natural wetlands differently depending on hydrological seasonality. Little Blue Herons were primarily consuming large anurans and anuran larvae, which are characteristic of agriculturally modified wetlands. The seasonal process of receding water levels in GIWs and subsequent concentration of
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013012
Subject Headings
Wetlands--Georgia, Wading birds, Herons--Ecology
Format
Document (PDF)
REPRODUCTIVE RESPONSES OF THREE HERON SPECIES TO VARIABLE FORAGING CONDITIONS AND NESTING ISLAND TYPE IN A MANAGED LAKE ECOSYSTEM
Title
REPRODUCTIVE RESPONSES OF THREE HERON SPECIES TO VARIABLE FORAGING CONDITIONS AND NESTING ISLAND TYPE IN A MANAGED LAKE ECOSYSTEM.
Creator
Evans, Jacquelyn D., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
Abstract/Description
The relationship between water-level fluctuations and wading bird nest numbers and nesting location is well documented, yet species-specific reproductive responses of wading birds to environmental drivers and nesting habitat type is poorly understood. Here, I compared the reproductive responses of two ecologically similar species, Snowy Egret and Tricolored Heron, to foraging conditions influenced by water management and examined the effect of nestling island type on the reproductive success...
Show moreThe relationship between water-level fluctuations and wading bird nest numbers and nesting location is well documented, yet species-specific reproductive responses of wading birds to environmental drivers and nesting habitat type is poorly understood. Here, I compared the reproductive responses of two ecologically similar species, Snowy Egret and Tricolored Heron, to foraging conditions influenced by water management and examined the effect of nestling island type on the reproductive success of three wading bird species. Reproductive responses to foraging conditions were broadly similar between Snowy Egrets and Tricolored Herons, however this study revealed specific-specific differences that could lead to different population dynamics in response to management over the long-term. I also found that these two species had lower productivity at spoil islands than marsh colonies, whereas Great Egret productivity did not vary by colony type. This study demonstrates the importance of establishing species-species relationships between productivity and environmental conditions
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Date Issued
2020
PURL
http://purl.flvc.org/fau/fd/FA00013550
Subject Headings
Herons--Ecology, Reproduction, Nesting behavior, Okeechobee, Lake (Fla), Species
Format
Document (PDF)
The Associations of Little Blue Heron Prey and Vegetation Communities in Two Subtropical Coastal Ecosystems
Title
The Associations of Little Blue Heron Prey and Vegetation Communities in Two Subtropical Coastal Ecosystems.
Creator
Kohler, Emilie R., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Shallow water availability coupled with anthropogenic degradation of seagrass beds limits wading bird food resources in dynamic coastal ecosystems. Identifying prey species critical to wading bird reproductive success and the environmental drivers of key prey species abundance is important for understanding how environmental stressors influence prey and change the quality of foraging patches. Little Blue Herons (Egretta caerulea) are reportedly generalists eating insects, crustaceans, and...
Show moreShallow water availability coupled with anthropogenic degradation of seagrass beds limits wading bird food resources in dynamic coastal ecosystems. Identifying prey species critical to wading bird reproductive success and the environmental drivers of key prey species abundance is important for understanding how environmental stressors influence prey and change the quality of foraging patches. Little Blue Herons (Egretta caerulea) are reportedly generalists eating insects, crustaceans, and fish; however, the proportions of prey items in the diet may shift spatially and temporally from freshwater to marine systems during breeding and non-breeding periods. I investigated prey selection by Little Blue Herons in Florida at the Great White Heron National Wildlife Refuge and the western Florida Bay, during 2016 and 2017 breeding seasons by investigating prey availability at low-tide locations along mudflats compared to stomach regurgitate samples collected from Little Blue Heron chicks 1 to 4 weeks old. Little Blue Herons selected Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) from the estuarine environment, but also consumed terrestrial prey (e.g. tree crabs) suggesting Little Blue Heron foraging habitat is not restricted to tidal flats. Additionally, these results support the characterization of Little Blue Herons as a generalist. After identifying important prey species, I modeled the associations of selected prey species with submerged aquatic vegetation density and abiotic variables to better understand habitat preferences and important habitat characteristics that drive prey density. Models support total seagrass density and algal density as having the greatest effect on prey selected by Little Blue Herons. Prawn density has a strong positive association with seagrass density. Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) had strong positive association with algae while pipefish (Syngnathidae) had a strong negative association with algae suggesting algae density in seagrass meadows should be considered when assessing the quality of seagrass meadows for Little Blue Heron prey and habitat suitability. My results varied from previous studies where prawns and gulf toadfish were associated with specific seagrass species. Therefore, some Little Blue Heron prey species in south Florida may not be affected by changes in submerged aquatic vegetation community composition if submerged aquatic vegetation densities remain constant. Studies are needed that clarify the complex interactions between prey and specific habitat metrics to validate the strength of landscape scale drivers of wading bird prey densities in dynamic coastal ecosystems and to determine how these communities will respond to anthropogenic environmental change.
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Date Issued
2018
PURL
http://purl.flvc.org/fau/fd/FA00013156
Subject Headings
Herons--Ecology, Egretta, Great White Heron National Wildlife Refuge (Fla), Florida Bay (Fla), Coastal ecology--Florida
Format
Document (PDF)